15 



If this olive-coloured residue be boiled in dilute spirit, the optical 

 crystals deposit on cooling. 



From the addition of 5'32 per cent, water to this dry residue, we 

 find that the silky crystals contain dry residue, 



94-678 = 949=1 atom 

 Water 5'322 = 54 = 6 atoms 



100-000 1003 



and we have thus the following formula for the silky salt, which 

 corresponds most closely with the result of analysis, 



C 57 H 33 N 2 O 5 1 



3 V2S0 3 HO + 9HO=1003, 



as may be seen by the following comparison : 



Consequently the silky salt will be the optical salt + 4 atoms of 

 water, which, under the influence of excess of sulphuric acid and 

 prolonged delay at 62 Fahr., are assimilated by that salt ; and 

 which additional water, on boiling in spirit, is lost, and the optical 

 salt recrystallized on cooling. 



If the temperature be not too high at first, the silky crystals 

 may be produced without the appearance of the optical. And the 

 silky crystals at 212, or at 62 Fahr. over sulphuric acid, become the 

 dry residue or tri-hydrate, which, when boiled in spirit, becomes the 

 optical, by assimilating 2 atoms of water, as may be seen by com- 

 paring the three proposed formulae : 



a. Optical. 

 C 57 H 33 N 2 O 5 



